Question: Does the speed vary depending on which mode (eco/sport/turbo) on is in and/or does it vary depending on which manual assist gear (ENVILOLO) one is? ....or do neither of this make a difference?
It is an interesting question. I have used the Walk Assist in numerous situations from walking my Specialized e-bikes upstairs to climbing a steep railway embankment (both situations actually occured on a demanding ride yesterday!)
I think Walk Assist is a distinct Mode, and it works the way to rotate the chainring cranks at the same speed you are walking your e-bike. I have just proven it by setting all the modes to 0/10% using Mission Control. Upon activating Walk Assist, the e-bike still provided the walk assistance. Moreover, the performance of the rear wheel did not depend on the assistance set to ECO, SPORT or TURBO modes! The Walk Assist must be a separate Assist Mode then.
The Walk Assist acts on the rear wheel through the drivetrain: set a high gear and the rear wheel will try to spin fast but it will deliver a little of torque. Set the gear to the lowest one and you will get max torque but the wheel would rotate deadly slowly.
Pushing and keeping the Walk Assist button depressed will deliver only 3 seconds of assistance if you
do not walk your e-bike (I have proven that, too). It is probably done so you cannot
ride your e-bike. However, the Walk Assist remains active as long as you keep the button depressed
and walk the e-bike all the way.
My driveway is up a steep incline and I find walk mode is extremely slow and sometimes fails to engage. Any insights appreciated.
The Walk Assist might be slow to engage. With the Specialized e-bikes that have the Walk Assist on the "+" button, the system needs a short while to determine if you are just increasing the assistance (short press) or requesting Walk Assist (long press and keeping the button depressed). If you are not walking your Como at the proper pace (which might be very slow or pretty fast, depending on the incline), the Walk Assist might disengage.
I have found Specialized Walk Assist being the most effective on extremely steep climbs. Your situation might require you set the manual gear in the middle or higher gear: You need to do some experiments!
Yesterday, I could walk my fully loaded Vado SL up very steep stairs using Walk Assist. As the speed was extremely low (like, crawling), I had my e-bike in a very low gear.